US20110005243A1

US20110005243A1 - Methods and systems for utilizing a micro-channel heat-exchanger device in a refrigeration circuit

Info

Publication number: US20110005243A1
Application number: US12/677,427
Authority: US
Inventors: Salvatore Macri
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2007-09-14
Filing date: 2007-09-14
Publication date: 2011-01-13
Also published as: EP2198215B1; ES2728398T3; EP2198215A4; HK1156390A1; WO2009035440A1; EP2198215A1; CN102016455A; CN102016455B

Abstract

A mini-channel heat-exchanger for a refrigeration circuit having an inlet manifold; a first return manifold; a first heat exchange pass in fluid communication between the inlet manifold and the first return manifold, the first heat exchange pass including a plurality of mini-channels; and a system charge tank in direct fluid communication with the first return manifold.

Description

BACKGROUND OF THE INVENTION

The present disclosure is related to a refrigeration circuit. More particularly, the present disclosure is related to a refrigeration circuit having a mini-channel heat-exchanger and a system charge tank.

DESCRIPTION OF RELATED ART

Refrigeration circuits are typically used in a number of devices in order to condition (e.g., cool, dehumidify, etc) ambient air within a predefined space such as, but not limited to, a house, a building, a car, a refrigerator, a freezer, and other conditioned spaces. A typical refrigeration circuit contains at least a compressor, a condenser, a receiver, a series of valves, at least one evaporator, and a system charge of refrigerant, which circulates throughout the circuit.
Periodically, various components of the circuit need to be serviced, repaired, and/or replaced. In order to do so, the system charge must be removed from the components that will need servicing. One method that is currently used to prepare the circuit for servicing is to drain all of the system charge from the circuit. The system charge can not be re-used and must be disposed of. Due to various environmental regulations, costs associated with the proper disposal of the spent system charge can be great. Therefore, this method may be undesirable.
A second method commonly used to prepare a circuit for servicing involves a “system pumpdown”. In a system pumpdown, the compressor is used to compress all of the system charge into a designated area within the circuit. This is advantageous in that it avoids having to remove and dispose of the system charge thereby, avoiding disposal costs and costs associated with new system charge.
In order for a system pumpdown to be effective, the designated storage area must have sufficient volume in which to store the compressed charge. Problems arise, however, when modifications to the circuit are made within the designated area, that reduce the volume available for storage. For example, in some refrigeration circuits, the condenser is included in the designated storage area. Round tube and fin condenser (“RTF”) coils are frequently used in condensers. RTF coils have large internal volumes and provide sufficient space so that the compressed system charge can be stored within the storage area. However, when mini-channel heat-exchanger (“MCHX”) coils are substituted for the RTF coils, there is a reduction in storage volume. The heat transfer coefficient is higher for MCHX type construction than for RTF, so whenever this type of replacement is made for coils of equal capacity the internal volume (storage area) will be reduced. Problems will, therefore, arise during a system pumpdown as there is not sufficient space to store the compressed system charge.

BRIEF SUMMARY OF THE INVENTION

A mini-channel heat-exchanger for a refrigeration circuit having an inlet manifold; a first return manifold; a first heat exchange pass in fluid communication between the inlet manifold and the first return manifold, the first heat exchange pass including a plurality of mini-channels; and a system charge tank in direct fluid communication with the first return manifold.
A method of performing a system pumpdown in an air conditioning system having a refrigeration circuit. The method includes closing a first valve; running a compressor until all of a system charge has been compressed between the compressor and the first valve and liquid system charge fills a portion of a mini-channel heat-exchanger and a system charge tank, the system charge tank being fluidly connected to the mini-channel heat-exchanger.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic representation of an exemplary embodiment of a refrigeration circuit according to the present disclosure.

FIG. 2 is a side view of a mini-channel heat-exchanger with an integrated system charge tank in vertical orientation according to the present disclosure.

FIG. 3 is a top view of a first exemplary embodiment of the heat-exchanger of FIG. 2 configured for use in a vertical orientation according to the present disclosure.

FIG. 4 is a side view of a second exemplary embodiment of the heat-exchanger of FIG. 2 configured for use in a horizontal orientation according to the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings and in particular to FIG. 1, an exemplary embodiment of a refrigeration circuit according to the present disclosure, generally referred to by reference numeral 10, is shown. Refrigeration circuit 10 includes a system charge tank (“tank”) 12 that can be used to store system charge during a system pump down. In the illustrated embodiment, tank 12 is shown in use with a mini-channel heat-exchanger, which for purposes of clarity is illustrated as a condenser 14. During normal cooling using circuit 10, tank 12 is full of flowing refrigerant in a gaseous state. However, tank 12 is configured to be filled with refrigerant in a liquid state during the system pump down.
Refrigeration circuit 10 includes tank 12, condenser 14, a compressor 18, an evaporator 20, a first valve 22, a second valve 24, a system charge of refrigerant 30, and an expansion device 40. During operation, refrigeration circuit 10 operates in a known manner. Operation of refrigeration circuit 10 is made with reference to FIGS. 1, 2, and 3.
Compressor 18 compresses system charge 30, which flows uninterrupted from the compressor to condenser 14. Condensor 14 includes a plurality of mini-channels 16 arranged in a plurality of heat-exchange passes.
Compressed system charge 30 in a gaseous state flows into condenser 14 through first inlet 32 into an inlet manifold 32-1. Inlet manifold 32-1 distributes the flow of charge 30 into a first pass 16-1.
Circuit 10 includes at least one condenser fan (not shown) that propels ambient outside air over condenser 14 enabling a heat-exchange between system charge 30 and the ambient outside air. During the heat-exchange between system charge 30 and the ambient outside air, the system charge begins to change from a gaseous state to a liquid state. After passing through the first pass 16, system charge 30 is collected in a first return manifold 36-1.
Tank 12 is in fluid communication with first return manifold 36-1 through a plurality of conduits 38-1, 38-2. In one embodiment of the present disclosure, plurality of conduits 38 is a set of holes so that tank 12 is integral with condenser 14. In another embodiment, plurality of conduits 38 may be pipes so that tank 12 can be remote from condenser 14.
Tank 12 has a length (L_T) that is substantially equal to the length of first return manifold 36-1 (L_M). In this manner, the upper conduit 38-1 is positioned at or near the top of the first return manifold, while the lower conduit 38-2 is positioned at or near the bottom of the first return manifold. Moreover, it is preferred that a floor (F_T) of tank 12 is co-planar with or slightly higher than a floor (F_M) of manifold 36-1.
As seen in FIGS. 2 and 3, condenser 14 is configured for arrangement in a substantially vertical position in refrigeration circuit 10.
Return manifold 36-1 distributes the flow of charge 30 into a second pass 16-2. After passing through the second pass 16-2, system charge 30 is collected in a second return manifold 36-2, which distributes the flow of charge 30 into a third pass 16-3. After passing through the third pass 16-3, system charge 30 is collected in a third return manifold 36-3, which distributes the flow of charge 30 into a fourth pass 16-4. After passing through the fourth pass 16-4, system charge 30 is collected in an outlet manifold 34-1, which passes the collected system charge out of condenser 14 at an outlet 34.
Accordingly, condenser 14 is illustrated by way of example as a four-pass mini-channel heat-exchanger. However, it is contemplated by the present disclosure for condenser 14 to have as few as one pass and as many passes as desired for the proper operation of circuit 10.
Condenser 14 is fluidly connected to expansion device 40 such that system charge 30 flows from the condenser uninterrupted to the expansion device. In some embodiments, the position of expansion device 40 can be changed from a fully open position to a fully closed position, and any position therebetween. When expansion device 40 is in a fully closed position, system charge 30, in a liquid state, will collect at the expansion device until such time that the expansion device is opened. Expansion device 40 can be any known expansion device such as, but not limited to, a fixed expansion device (e.g., an orifice) or a controllable expansion device (e.g., a thermal expansion valve).
When expansion device 40 is opened, system charge 30 flows uninterrupted to first valve 22. First valve 22 can be opened or closed either manually or by means of electrical communication from a controller (not shown). During normal operation of refrigeration circuit 10, first valve 22 is open such that system charge 30 can flow continuously to evaporator 20. As system charge 30 flows through evaporator 20, system charge 30 is in heat-exchange communication with a working fluid (not shown) to condition the working fluid. It is contemplated by the present disclosure that the working fluid can be ambient indoor air or a secondary loop fluid such as, but not limited to, chilled water or glycol.
System charge 30 then exits evaporator 20 and flows continuously to second valve 24. Second valve 24 can be in either an open or closed position and its position can be changed either manually or via electrical communication from a controller (not shown). When second valve 24 is opened, system charge 30 flows uninterrupted from evaporator 20 to compressor 18.
During a system pumpdown, first valve 22 is closed and compressor 18 is run. As compressor 18 runs, compressed system charge 30 flows through condenser 14 wherein the system charge is changed from a gaseous to liquid state. Liquid system charge 30 will then collect at first valve 22 and will then be collected in the condenser. As the level of liquid system charge 30 increases in condenser 14, the liquid system charge will flow through and be collected in the condenser in a reverse order to the normal direction of flow of the system charge. For example, the liquid system charge 30 will first be collected in outlet manifold 34-1, fourth pass 16-4, and third return manifold 36-3. The collection of liquid system charge 30 will continue until the liquid level reaches the bottom conduit 38-2. Once the fluid level reaches the bottom conduit 38-2, the liquid system charge 30 is collected in tank 12, as well as in the remaining portions of condenser 14.
Thus, in the embodiment of FIGS. 2 and 3, tank 12 is positioned on first return manifold 36-1 so that flow of system charge 30 through first and second conduits 38-1, 38-2 is in a horizontal direction.
Compressor 18 will continue to run until all of system charge 30 has been compressed at which time second valve 24 will be closed. Upon completion of the pumpdown, all of compressed system charge 30 will be stored in outside portion 28 of refrigeration circuit 10 between first and second valves 22, 24. Advantageously, outside portion 28 can be dissociated from inside portion 26 allowing for the inside portion to be serviced without replacing any of system charge 30.
Once servicing of circuit 10 is completed, outside portion 28 and inside portion 26 can be reconnected. First valve 22 and second valve 24 can then be opened. It is contemplated that first and second valves 22, 24 can be either fully opened or partially opened either manually or through electrical communication from a controller (not shown). As such, system charge 30 can now flow freely throughout refrigeration circuit 10. Compressor 18 is turned on and system charge 30 circulates throughout circuit 10.
As seen in FIG. 4, an alternate exemplary embodiment of condenser 14 is shown. Here, condenser 14 is configured for arrangement in a substantially horizontal position in refrigeration circuit 10. More particularly, tank 12 is arranged with respect to a flow direction through mini-channels 16 so that there is an approximately ninety-degree angle between the tank and the mini-channels.
During a system pumpdown, liquid system charge 30 collects at first valve 22 and will then be collected in condenser 14. As the level of liquid system charge 30 increases in condenser 14, the liquid system charge will flow through and be collected in the condenser in a reverse order to the normal direction of flow of the system charge. For example, liquid system charge 30 will first be collected in outlet manifold 34-1, fourth pass 16-4, and third return manifold 36-3. The collection of liquid system charge 30 continues until the liquid level reaches bottom conduit 38-2. Once the fluid level reaches bottom conduit 38-2, the liquid system charge 30 is collected in tank 12, as well as the remaining portions of condenser 14.
Thus, in FIG. 4, tank 12 is positioned on first return manifold 36-1 so that the flow of system charge 30 through first and second conduits 38-1, 38-2 is in a vertical direction.
Thus, in the embodiment of FIG. 4, tank 12 is positioned on first return manifold 36-1 so that flow of system charge 30 through first and second conduits 38-1, 38-2 is in a vertical direction.
It should be noted that tank 12 is described in use with condenser 14. However, it is contemplated by the present disclosure for tank 12 to find equal use with evaporator 20.
It should also be noted that the terms “first”, “second”, “third”, “upper”, “lower”, and the like may be used herein to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated.
While the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.

Claims

1. A mini-channel heat-exchanger for a refrigeration circuit, comprising:

an inlet manifold;

a first return manifold;

a first heat exchange pass in fluid communication between said inlet manifold and said first return manifold, said first heat exchange pass including a plurality of mini-channels; and

a system charge tank in direct fluid communication with said first return manifold.

2. The heat-exchanger as in claim 1, further comprising an outlet manifold and a second heat exchange pass, said second heat exchange pass being in fluid communication between said first return manifold and said outlet manifold.

3. The heat-exchanger as in claim 1, further comprising:

a first conduit placing top portions of said first return manifold and said system charge tank in direct fluid communication with one another; and

a second conduit placing bottom portions of said first return manifold and said system charge tank in direct fluid communication with one another.

4. The heat-exchanger as in claim 3, wherein said system charge tank is positioned on said first return manifold so that said first and second conduits are configured for flow in a horizontal direction.

5. The heat-exchanger as in claim 3, wherein said system charge tank is positioned on said first return manifold so that said first and second conduits are configured for flow in a vertical direction.

6. The heat-exchanger as in claim 3, wherein said first return manifold and said system charge tank are integrally formed with one another and said first and second conduits comprise holes.

7. The heat-exchanger as in claim 6, wherein said system charge tank has a tank floor and said first return manifold has a manifold floor, said second conduit being substantially co-planar with said tank and manifold floors.

8. The heat-exchanger as in claim 3, wherein said first return manifold and said system charge tank are remote from one another and said first and second conduits comprise pipes.

9. The heat-exchanger as in claim 1, wherein said system charge tank has a tank length and said first return manifold has a manifold length, said tank length being substantially equal to said manifold length.

10. The heat-exchanger as in claim 1, wherein said system charge tank has a tank floor and said first return manifold has a manifold floor, said tank floor being co-planar with or slightly higher than said manifold floor.

11. A method of performing a system pumpdown in an air conditioning system having a refrigeration circuit, the method comprising the steps of:

closing a first valve;

running a compressor until all of a system charge has been compressed between said compressor and said first valve and liquid system charge fills a portion of a mini-channel heat-exchanger and a system charge tank, said system charge tank being fluidly connected to said mini-channel heat-exchanger.

12. The method of claim 11, further comprising closing a second valve after said compressor is turned off.

13. The method of claim 12, further comprising opening said first and second valves so that said system charge can be recirculated throughout the refrigeration circuit.

14. A refrigeration system, comprising:

a condenser having an inlet manifold, a first return manifold, a first heat exchange pass in fluid communication between said inlet manifold and said first return manifold, said first heat exchange pass including a plurality of mini-channels, and a system charge tank in direct fluid communication with said first return manifold;

a compressor; and

an evaporator.